Abstract

Lung cancer is the leading cause of cancer-related deaths in the United States, and the dismal 5-year survival rate of approximately 14% has shown no improvement over the past three decades. Cigarette smoke (CS) is the cause of ∼90% of lung cancer cases, and promotes drug resistance in lung cancer patients and is even known to limit effectiveness of treatment of cancers of other organs. It is therefore important to develop more effective strategies targeting CS-induced molecular abnormalities. Cigarette smoking increases oxidative stress particularly via activation of NADPH oxidase (NOX), a key source of superoxide anion production. Here we report the inhibitory effects of bioactive phytochemicals, grape seed proanthocyanidins (GSPs), on the migration potential of human non-small cell lung cancer (NSCLC) cells (A549, H460 and H1299) and assessed whether CS-induced NOX activation is their target. Using an in vitro invasion assay, we found that treatment of NSCLC cells with CS condensate (CSC) increased the migration of NSCLC cells in a dose-dependent manner, via enhancing NOX mediated-reactive oxygen species (ROS) accumulation. Treatment of NSCLC cells with GSPs inhibited the cell migration via reduction in ROS accumulation or oxidative stress and subsequent reduction of epithelial-to-mesenchymal transition. To examine the molecular targets of GSPs, we studied the effect of GSPs on CSC-induced alterations in the levels of key NOX components, namely, p22phox and p47phox, using A549 cells. We also determined the effect of GSPs on CSC-induced interaction between p22phox and p47phox proteins, a key event in NOX activation. Our results indicate that treatment of A549 cells with GSPs not only reverse CSC-induced expression levels of p22phox and p47phox, but also inhibit CSC-induced NOX activation by decreasing the binding of p22phox and p47phox proteins. This new insight into the anti-lung cancer cell migration activity of GSPs could serve as a basis for chemoprevention or therapy of advanced stage of lung cancer in human patients.